1. Field of the Invention
The present invention relates to a vapour-compression type refrigerating machine. More particularly, the present invention relates to a vapour-compression type refrigerating machine for vehicle use, that is, the present invention relates to an air-conditioner for vehicle use and a double pipe structure and double pipe joint structure provided with an inner pipe and outer pipe preferably used for this refrigerating machine.
2. Description of the Related Art
In the case of a conventional vapour-compression type refrigerating machine, a refrigerant pipe made of rubber, which is connected with the suction side of the compressor, and a refrigerant pipe made of rubber, which is connected with the discharge side of the compressor, are formed into a double cylindrical shape being integrated into one body. This structure is disclosed, for example, in the official gazette of Japanese Patent No. 2595578.
There is provided an invention in which a high pressure refrigerant passage communicating with the compressor, condenser and evaporator is integrated with a low pressure refrigerant passage. For example, this structure is disclosed in the official gazette of Japanese Unexamined Patent Publication No. 2001-277842.
However, according to the invention described in Japanese Patent No. 2595578, only the pipe connected with the compressor is integrated into one body. Therefore, it is difficult to further reduce the number of pipes and the number of joints to connect the pipes.
According to the invention described in Japanese Unexamined Patent Publication No. 2001-277842, the high pressure refrigerant passage and the low pressure refrigerant passage are integrated into one body. Therefore, refrigerant which has flowed out from the evaporator must be returned to the compressor via the condenser. Accordingly, the length of the low pressure refrigerant passage is extended by the length of the condenser. As a result, there is a high possibility that the pressure loss of refrigerant is increased and the power consumption of the compressor is increased. In general, in the air-conditioner composing a refrigerating cycle, pipe-shaped piping members are connected among the compressor, condenser, expansion valve and evaporator for circulating refrigerant. When the length of the piping members increases, the manufacturing cost is raised. Therefore, in the case of an air-conditioner, investigations have been made into the arrangement of each device so that the piping length can be made as short as possible. However, in the case of an air-conditioner mounted on a vehicle, for example, when an air-conditioner is mounted on a one-box type vehicle, the length of piping is greatly increased to lay the piping members for the rear seat evaporator.
In order to solve the above problems, it is conventional to use a double pipe so that the length of piping can be reduced. For example, in Japanese Unexamined Patent Publication No. 2001-235081, the double pipe 71 is described which is composed in such a manner that the inner pipe 72 and the outer pipe 73 are integrally formed into one body by means of extrusion or drawing. According to this double pipe 71, as shown in FIGS. 18 and 19, the inner pipe 72 and the outer pipe 73 are connected with each other by the connecting ribs 74, which are radially arranged, connecting the outer circumferential face of the inner pipe 72 with the inner circumferential face of the outer pipe 73. At the end portion, a forward end portion of the outer pipe 73 is cut off so that the inner pipe 72 can be protruded from the outer pipe 73, and the inner pipe 72 is joined to the joint member 80. Further, the forward end portion of the outer pipe 73 is closed, and the pipe-shaped connecting member 75, which surrounds the protruding inner pipe 72, is joined between the protruding portion 72a of the inner pipe 72 and the outer pipe 73. In order to connect the passage of fluid flowing in the outer pipe 73 with the joint member 80, the connection member 75 is connected with the joint member 80 via the piping member 76 for the use of extension.
As shown in FIG. 12, this double pipe 71 is applied to an air-conditioner for automobile use mounted on a one-box type vehicle and laid in the passage from the air-conditioner 51, which is arranged outside the passenger's chamber, to the air-conditioner unit 61 used for a rear seat.
The double pipe is originally employed for the object of reducing the manufacturing cost by decreasing the piping length. Therefore, it is not preferable that, for example, the structure of connecting the joint member becomes complicated and the manufacturing cost is raised. For example, according to the structure shown in the official gazette of Japanese Unexamined Patent Publication 2001-235081, in order to protrude the inner pipe 72, it is necessary to cut off the forward end portion of the outer pipe 73, which increases the machining cost. Further, as an outer pipe passage, it is necessary to arrange the piping member 76 used for extension in the joint member 80. Therefore, the manufacturing cost is increased for arranging the connecting member 75. As a result, the manufacturing cost is increased.
As described in the official gazette of Japanese Unexamined Patent Publication No. 2001-235081, the double pipe structure is composed in such a manner that the inner and the outer pipe are formed different from each other, the inner pipe is inserted into the outer pipe and then an end portion of the outer pipe is connected to the inner pipe with pressure by means of drawing so that the inner and the outer pipe can be integrated into one body. According to this structure, the manufacturing cost is increased when the end portion of the outer pipe is subjected to drawing so that the end portion of the outer pipe can be connected to the inner pipe with pressure. Further, it is necessary to newly compose a structure for joining the joint member.
Further, the double pipe joint structure for connecting this double pipe is disclosed in the official gazette of Japanese Unexamined Patent Publication No. 2001-235081.
According to this double pipe, as shown in FIG. 36, the inner pipe 72 and the outer pipe 73 are connected with each other by the connecting ribs, which are radially arranged, connecting the outer circumferential face of the inner pipe 72 with the inner circumferential face of the outer pipe 73. At the end portion, a forward end portion of the outer pipe 73 is cut off so that the inner pipe 72 can be protruded from the outer pipe 73, and the inner pipe 72 is joined to the joint member 80. Further, the forward end portion of the outer pipe 73 is closed, and the pipe-shaped connecting member 75, which surrounds the protruding inner pipe 72, is joined between the protruding portion 72a of the inner pipe 72 and the outer pipe 73. In order to connect the passage of fluid flowing in the outer pipe 73 with the joint member 80, the connection member 75 is connected with the joint member 80 via the piping member 76 for the use of extension.
The forward end portion of the inner pipe 72 and the forward end portion of the piping member 76 used for extension are connected with the first joint member 80. After the male portions 81, 82, which are formed in the first joint member 80, have been respectively joined to the female portions of the second joint member 85 connected with the two different piping members, the first joint member 80 is connected with the second joint member 85 by the bolts 86 and others.
Further, in the joint member for connecting these double pipes, the male portions 81, 82 of the first joint member 80 to connect the inner pipe 72 with the outer pipe 73 of one double pipe 71 are connected with the female portions of the second joint member 85 to connect two piping members which are laid differently, and then the male portions and the female portions are connected by the bolts 86 and others. Therefore, it is impossible to instantly connect the double pipe 71 with the joint member 80. Therefore, it takes time and much labor to make the connection. Further, the first joint member 80 and the second joint member 85 are respectively joined to the inner pipe 72 and the outer pipe 73 (the piping member 76 used for extension) by means of soldering or welding. Accordingly, the sizes of the respective joint members are increased, and it takes time to join the inner pipe to the outer pipe.